diff --git a/android/Android.bp b/android/Android.bp
index da36959..d3540b2 100644
--- a/android/Android.bp
+++ b/android/Android.bp
@@ -16,7 +16,9 @@
         "soong-remoteexec",
         "soong-response",
         "soong-shared",
+        "soong-starlark-format",
         "soong-ui-metrics_proto",
+
         "golang-protobuf-proto",
         "golang-protobuf-encoding-prototext",
 
diff --git a/android/config.go b/android/config.go
index 10e074c..f10732b 100644
--- a/android/config.go
+++ b/android/config.go
@@ -38,6 +38,7 @@
 	"android/soong/android/soongconfig"
 	"android/soong/bazel"
 	"android/soong/remoteexec"
+	"android/soong/starlark_fmt"
 )
 
 // Bool re-exports proptools.Bool for the android package.
@@ -286,14 +287,12 @@
 		}
 	}
 
-	//TODO(b/216168792) should use common function to print Starlark code
-	nonArchVariantProductVariablesJson, err := json.MarshalIndent(&nonArchVariantProductVariables, "", "    ")
+	nonArchVariantProductVariablesJson := starlark_fmt.PrintStringList(nonArchVariantProductVariables, 0)
 	if err != nil {
 		return fmt.Errorf("cannot marshal product variable data: %s", err.Error())
 	}
 
-	//TODO(b/216168792) should use common function to print Starlark code
-	archVariantProductVariablesJson, err := json.MarshalIndent(&archVariantProductVariables, "", "    ")
+	archVariantProductVariablesJson := starlark_fmt.PrintStringList(archVariantProductVariables, 0)
 	if err != nil {
 		return fmt.Errorf("cannot marshal arch variant product variable data: %s", err.Error())
 	}
diff --git a/android/soong_config_modules_test.go b/android/soong_config_modules_test.go
index acb9d18..ceb8e45 100644
--- a/android/soong_config_modules_test.go
+++ b/android/soong_config_modules_test.go
@@ -386,6 +386,46 @@
 	})).RunTest(t)
 }
 
+func TestDuplicateStringValueInSoongConfigStringVariable(t *testing.T) {
+	bp := `
+		soong_config_string_variable {
+			name: "board",
+			values: ["soc_a", "soc_b", "soc_c", "soc_a"],
+		}
+
+		soong_config_module_type {
+			name: "acme_test",
+			module_type: "test",
+			config_namespace: "acme",
+			variables: ["board"],
+			properties: ["cflags", "srcs", "defaults"],
+		}
+    `
+
+	fixtureForVendorVars := func(vars map[string]map[string]string) FixturePreparer {
+		return FixtureModifyProductVariables(func(variables FixtureProductVariables) {
+			variables.VendorVars = vars
+		})
+	}
+
+	GroupFixturePreparers(
+		fixtureForVendorVars(map[string]map[string]string{"acme": {"feature1": "1"}}),
+		PrepareForTestWithDefaults,
+		FixtureRegisterWithContext(func(ctx RegistrationContext) {
+			ctx.RegisterModuleType("soong_config_module_type_import", SoongConfigModuleTypeImportFactory)
+			ctx.RegisterModuleType("soong_config_module_type", SoongConfigModuleTypeFactory)
+			ctx.RegisterModuleType("soong_config_string_variable", SoongConfigStringVariableDummyFactory)
+			ctx.RegisterModuleType("soong_config_bool_variable", SoongConfigBoolVariableDummyFactory)
+			ctx.RegisterModuleType("test_defaults", soongConfigTestDefaultsModuleFactory)
+			ctx.RegisterModuleType("test", soongConfigTestModuleFactory)
+		}),
+		FixtureWithRootAndroidBp(bp),
+	).ExtendWithErrorHandler(FixtureExpectsAllErrorsToMatchAPattern([]string{
+		// TODO(b/171232169): improve the error message for non-existent properties
+		`Android.bp: soong_config_string_variable: values property error: duplicate value: "soc_a"`,
+	})).RunTest(t)
+}
+
 func testConfigWithVendorVars(buildDir, bp string, fs map[string][]byte, vendorVars map[string]map[string]string) Config {
 	config := TestConfig(buildDir, nil, bp, fs)
 
diff --git a/android/soongconfig/Android.bp b/android/soongconfig/Android.bp
index 9bf3344..8fe1ff1 100644
--- a/android/soongconfig/Android.bp
+++ b/android/soongconfig/Android.bp
@@ -10,6 +10,7 @@
         "blueprint-parser",
         "blueprint-proptools",
         "soong-bazel",
+        "soong-starlark-format",
     ],
     srcs: [
         "config.go",
diff --git a/android/soongconfig/modules.go b/android/soongconfig/modules.go
index 09a5057..212b752 100644
--- a/android/soongconfig/modules.go
+++ b/android/soongconfig/modules.go
@@ -25,6 +25,8 @@
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/parser"
 	"github.com/google/blueprint/proptools"
+
+	"android/soong/starlark_fmt"
 )
 
 const conditionsDefault = "conditions_default"
@@ -177,10 +179,14 @@
 		return []error{fmt.Errorf("values property must be set")}
 	}
 
+	vals := make(map[string]bool, len(stringProps.Values))
 	for _, name := range stringProps.Values {
 		if err := checkVariableName(name); err != nil {
 			return []error{fmt.Errorf("soong_config_string_variable: values property error %s", err)}
+		} else if _, ok := vals[name]; ok {
+			return []error{fmt.Errorf("soong_config_string_variable: values property error: duplicate value: %q", name)}
 		}
+		vals[name] = true
 	}
 
 	v.variables[base.variable] = &stringVariable{
@@ -235,7 +241,12 @@
 // string vars, bool vars and value vars created by every
 // soong_config_module_type in this build.
 type Bp2BuildSoongConfigDefinitions struct {
-	StringVars map[string]map[string]bool
+	// varCache contains a cache of string variables namespace + property
+	// The same variable may be used in multiple module types (for example, if need support
+	// for cc_default and java_default), only need to process once
+	varCache map[string]bool
+
+	StringVars map[string][]string
 	BoolVars   map[string]bool
 	ValueVars  map[string]bool
 }
@@ -253,7 +264,7 @@
 	defer bp2buildSoongConfigVarsLock.Unlock()
 
 	if defs.StringVars == nil {
-		defs.StringVars = make(map[string]map[string]bool)
+		defs.StringVars = make(map[string][]string)
 	}
 	if defs.BoolVars == nil {
 		defs.BoolVars = make(map[string]bool)
@@ -261,15 +272,24 @@
 	if defs.ValueVars == nil {
 		defs.ValueVars = make(map[string]bool)
 	}
+	if defs.varCache == nil {
+		defs.varCache = make(map[string]bool)
+	}
 	for _, moduleType := range mtDef.ModuleTypes {
 		for _, v := range moduleType.Variables {
 			key := strings.Join([]string{moduleType.ConfigNamespace, v.variableProperty()}, "__")
+
+			// The same variable may be used in multiple module types (for example, if need support
+			// for cc_default and java_default), only need to process once
+			if _, keyInCache := defs.varCache[key]; keyInCache {
+				continue
+			} else {
+				defs.varCache[key] = true
+			}
+
 			if strVar, ok := v.(*stringVariable); ok {
-				if _, ok := defs.StringVars[key]; !ok {
-					defs.StringVars[key] = make(map[string]bool, 0)
-				}
 				for _, value := range strVar.values {
-					defs.StringVars[key][value] = true
+					defs.StringVars[key] = append(defs.StringVars[key], value)
 				}
 			} else if _, ok := v.(*boolVariable); ok {
 				defs.BoolVars[key] = true
@@ -302,29 +322,16 @@
 // String emits the Soong config variable definitions as Starlark dictionaries.
 func (defs Bp2BuildSoongConfigDefinitions) String() string {
 	ret := ""
-	ret += "soong_config_bool_variables = {\n"
-	for _, boolVar := range sortedStringKeys(defs.BoolVars) {
-		ret += fmt.Sprintf("    \"%s\": True,\n", boolVar)
-	}
-	ret += "}\n"
-	ret += "\n"
+	ret += "soong_config_bool_variables = "
+	ret += starlark_fmt.PrintBoolDict(defs.BoolVars, 0)
+	ret += "\n\n"
 
-	ret += "soong_config_value_variables = {\n"
-	for _, valueVar := range sortedStringKeys(defs.ValueVars) {
-		ret += fmt.Sprintf("    \"%s\": True,\n", valueVar)
-	}
-	ret += "}\n"
-	ret += "\n"
+	ret += "soong_config_value_variables = "
+	ret += starlark_fmt.PrintBoolDict(defs.ValueVars, 0)
+	ret += "\n\n"
 
-	ret += "soong_config_string_variables = {\n"
-	for _, stringVar := range sortedStringKeys(defs.StringVars) {
-		ret += fmt.Sprintf("    \"%s\": [\n", stringVar)
-		for _, choice := range sortedStringKeys(defs.StringVars[stringVar]) {
-			ret += fmt.Sprintf("        \"%s\",\n", choice)
-		}
-		ret += fmt.Sprintf("    ],\n")
-	}
-	ret += "}"
+	ret += "soong_config_string_variables = "
+	ret += starlark_fmt.PrintStringListDict(defs.StringVars, 0)
 
 	return ret
 }
diff --git a/android/soongconfig/modules_test.go b/android/soongconfig/modules_test.go
index b14f8b4..a7800e8 100644
--- a/android/soongconfig/modules_test.go
+++ b/android/soongconfig/modules_test.go
@@ -367,19 +367,19 @@
 
 func Test_Bp2BuildSoongConfigDefinitions(t *testing.T) {
 	testCases := []struct {
+		desc     string
 		defs     Bp2BuildSoongConfigDefinitions
 		expected string
 	}{
 		{
+			desc: "all empty",
 			defs: Bp2BuildSoongConfigDefinitions{},
-			expected: `soong_config_bool_variables = {
-}
+			expected: `soong_config_bool_variables = {}
 
-soong_config_value_variables = {
-}
+soong_config_value_variables = {}
 
-soong_config_string_variables = {
-}`}, {
+soong_config_string_variables = {}`}, {
+			desc: "only bool",
 			defs: Bp2BuildSoongConfigDefinitions{
 				BoolVars: map[string]bool{
 					"bool_var": true,
@@ -389,39 +389,35 @@
     "bool_var": True,
 }
 
-soong_config_value_variables = {
-}
+soong_config_value_variables = {}
 
-soong_config_string_variables = {
-}`}, {
+soong_config_string_variables = {}`}, {
+			desc: "only value vars",
 			defs: Bp2BuildSoongConfigDefinitions{
 				ValueVars: map[string]bool{
 					"value_var": true,
 				},
 			},
-			expected: `soong_config_bool_variables = {
-}
+			expected: `soong_config_bool_variables = {}
 
 soong_config_value_variables = {
     "value_var": True,
 }
 
-soong_config_string_variables = {
-}`}, {
+soong_config_string_variables = {}`}, {
+			desc: "only string vars",
 			defs: Bp2BuildSoongConfigDefinitions{
-				StringVars: map[string]map[string]bool{
-					"string_var": map[string]bool{
-						"choice1": true,
-						"choice2": true,
-						"choice3": true,
+				StringVars: map[string][]string{
+					"string_var": []string{
+						"choice1",
+						"choice2",
+						"choice3",
 					},
 				},
 			},
-			expected: `soong_config_bool_variables = {
-}
+			expected: `soong_config_bool_variables = {}
 
-soong_config_value_variables = {
-}
+soong_config_value_variables = {}
 
 soong_config_string_variables = {
     "string_var": [
@@ -430,6 +426,7 @@
         "choice3",
     ],
 }`}, {
+			desc: "all vars",
 			defs: Bp2BuildSoongConfigDefinitions{
 				BoolVars: map[string]bool{
 					"bool_var_one": true,
@@ -438,15 +435,15 @@
 					"value_var_one": true,
 					"value_var_two": true,
 				},
-				StringVars: map[string]map[string]bool{
-					"string_var_one": map[string]bool{
-						"choice1": true,
-						"choice2": true,
-						"choice3": true,
+				StringVars: map[string][]string{
+					"string_var_one": []string{
+						"choice1",
+						"choice2",
+						"choice3",
 					},
-					"string_var_two": map[string]bool{
-						"foo": true,
-						"bar": true,
+					"string_var_two": []string{
+						"foo",
+						"bar",
 					},
 				},
 			},
@@ -466,15 +463,17 @@
         "choice3",
     ],
     "string_var_two": [
-        "bar",
         "foo",
+        "bar",
     ],
 }`},
 	}
 	for _, test := range testCases {
-		actual := test.defs.String()
-		if actual != test.expected {
-			t.Errorf("Expected:\n%s\nbut got:\n%s", test.expected, actual)
-		}
+		t.Run(test.desc, func(t *testing.T) {
+			actual := test.defs.String()
+			if actual != test.expected {
+				t.Errorf("Expected:\n%s\nbut got:\n%s", test.expected, actual)
+			}
+		})
 	}
 }